Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason

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Question

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R :
Assertion A : Metallic sodium dissolves in liquid ammonia giving a deep blue solution, which is paramagnetic.
Reason R : The deep blue solution is due to the formation of amide.
In the light of the above statements, choose the correct answer from the options given below :
(1) Both A and R are true and R is the correct explanation of A
(2) Both A and R are true but R is NOT the correct explanation of A
(3) A is true but R is false
(4) A is false but R is true

Accepted Answer

Correct Answer: C — A is true but R is falseStep-by-step Solution:Assertion A (TRUE): When sodium (or any alkali metal) dissolves in liquid ammonia, a deep blue solution is formed. This solution is paramagnetic because it contains unpaired electrons — specifically, the free (solvated) electrons produced: Na → Na⁺(am) + e⁻(am). These ammoniated electrons (e⁻am) are responsible for the blue colour and paramagnetism.Reason R (FALSE): The reason incorrectly states that the blue colour is due to formation of amide (NaNH₂). Amide formation (Na + NH₃ → NaNH₂ + ½H₂) is a slow, subsequent reaction (catalysed by Fe³⁺ or other transition metals). NaNH₂ is colourless — it does NOT produce the blue colour. The blue colour is solely due to ammoniated (solvated) electrons, not amide formation.Therefore, Assertion is true but Reason is false → Option C.Key Concepts:Alkali metals dissolve in liquid NH₃ to give ammoniated electrons: M → M⁺(am) + e⁻(am).Ammoniated electrons are responsible for: (i) deep blue colour at dilute concentrations, (ii) bronze/copper colour at high concentration, (iii) paramagnetism due to unpaired electrons, (iv) strong reducing action.Amide formation: Na + NH₃ → NaNH₂ + ½H₂ — this is slow, occurs separately, and NaNH₂ is colourless.The solution conducts electricity due to mobile ammoniated electrons.

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